Agonists of opioid receptors are known to stimulate short-term feeding and antagonists of these receptors are known to decrease feeding. Also, circulating and central levels of opioids seems to increase during periods of eating and levels of some opioids are elevated in obese animals. Such data suggest that opioid receptors are important regulators of food intake. However, many detailed questions remain unanswered. We do not know whether opioids are directly involved in feeding, where the of unanswered. We do not now whether opioids are directly involved in feeding, where the neuroregulators act or which receptors specifically are involved. It is the intent of our grant to continues using some of the strategies we have used in the past and add some recently developed technologies to address questions about opioids and feeding. We will attempt to answer the following questions: (1) which opioid receptors are involved in regulating feeding? (2) what are the sites of action in the brain for opioid-induced feeding? and (3) are opioid effects on feeding behavior specific and do they motivate animals to eat? With the use of newly available opioid antagonists, we should better be able to identify the sites of actions and receptor types involved in feeding regulation. Using these same agents with operant chambers, we will be better equipped to address whether opioids specifically affect feeding or result in non-specific oral behaviors. Thus, we feel that behavioral approaches are necessary to answer the question: Are opioids important regulators of food intake?